Air conditioning system



C. L. RINGQUIST ET AL AIR CONDITIONING SYSTEM Filed Aug. 31, 1953 F eb. 22, 1955 INVEN TOR. CLARENCE L. RINGQUIST ROBERT G. MINER W @m ATTORNEYS AIR CONDITIONING SYSTEM Clarence L. Ringquist and Robert G. Miner, La Crosse, Wis., assignors to The Trane Company, La Crosse, WIS.

Application August 31, 1953, Serial No. 377,278

4 Claims. (Cl. 62-6) This invention relates to an air conditioning system for maintaining the desired temperature and humid ty in an enclosure, using refrigerating means for dehumidifying, cooling and/ or heating air supplied to the enclosure.

It is an object of this invention to provide refrigerating apparatus having an evaporator for cooling an an stream, a reheat condenser for heating said air stream and a secondary condenser for providing additlonal condensing capacity when required.

It is another object of the invention to maintain a constant pressure and temperature of the gas flowing through the reheat condenser so that the leaving air temperature can be controlled by varying the portion of the arr stream passing through the reheat condenser.

It is another object of the invention to provide a secondary condenser the capacity of which can be controlled to provide a substantially constant pressure and tempera ture in the reheat condenser.

Other objects and advantages of the invention will become apparent as the specification proceeds to describe the invention with reference to the drawing which shows diagrammatically the apparatus including the controls.

Referring now to the drawing, numeral designates an enclosure to which conditioned air is supplied to mamtain therein a substantially constant temperature and humidity.

A cabinet 12 has an opening 14 through wh1ch a1r flows into the cabinet and an opening 15 through which a 1r 1s supplied to the enclosure 10. This air may be entirely from outside the enclosure 10, or it may be entirely from the enclosure 10, or it may be a mixture of air from outside and inside the enclosure 10. A fan 16 moves the air through the cabinet 12. An evaporator 18 extends part way across the cabinet 12 to cool the air fiowmg through said evaporator. A condenser 20 extends part way across the cabinet 12 to heat the air flowing through said condenser. A refrigerant compressor 22 s driven by any suitable prime mover preferably an electric motor. Compressor 22 receives refrigerant from evaporator 18 through pipe 24 and discharges refrigerant through pipe 26 which conducts refrigerant to condenser 20. From condenser 20 the refrigerant flows to a receiver 28, and from receiver 28 the liquid refrigerant is conducted to the evaporator 18 through a pipe 30. solenoid l 1qu1d valve 32 controls the flow of liquid in pipe as will be described below.

From pipe 26 a branch pipe 34 extends to the condenser coil 36 of an evaporative condenser 38. From condenser coil 36 the refrigerant flows through pipe 40 to the receiver 28.

The evaporative condenser 38 has an alt supply duct 42, an air discharge duct 44, and an air return duct 46. A fan 48 driven by an electric motor 50 through belt 52 draws air into the evaporative condenser through duct 42 then upwardly through coil 36. Fan 48 discharges the air through duct 44 or 46 accordlng to the setting of dampers 54 and 56 in ducts 44 and 46 respectively. Dampers 58 in duct 42 move simultaneously with dampers 54 and 56 as will be described more fully. A pump 60 driven by motor 62 draws water from the bottom of evaporative condenser 38 and discharges said water into a spray tree 64 from which water is sprayed downwardly over condenser coil 36.

The control apparatus will now be described. A thermostat 66 and a humidistat 68 of the well known pneumatic type are mounted in enclosure 10 and are con- United States Patent 0 2,702,456 Patented Feb. 22, 1955 "ice nected to a source of air under pressure 70. A tube 72 extends from humidistat 68 to a duplex pressure selector 74, and a tube 76 extends from thermostat 66 to said duplex pressure selector 74. The duplex pressure selector 74 is a well known device for transmitting the higher of the pressures in tubes 72 and 76 to tube 78. Pneumatic damper motor 80 is connected to tube 78 to receive air pressure therefrom. Damper motor 80 is connected to position dampers 82 which control the flow through evaporator 18, and it is also connected to position dampers 84 which control the flow of air by-passing evaporator 18. A pneumatic pressure switch 86 is connected to a source of electrical energy and to tube 78 and is electrically connected by wire 88 to solenoid valve 32 and motor starter 90 of compressor 22.

A pneumatic damper motor 92 is connected to receive pressure from tube 76. Damper motor 92 is connected to position dampers 94 which control the flow through condenser coil 20, and damper motor 92 is also connected to position dampers 96 which control the flow of air bypassing condenser coil 20.

A pneumatic pressure controller 98 is connected to refrigerant pipe 34 and receives pressure from a source of air under pressure 100. Extending from pressure controller 98 is a tube 102 to which is connected a pneumat1c damper motor 104. Damper motor 104 is connected to position dampers 54, 56 and 58. A pneumatic pressure switch 106 is connected to a source of electrical energy, and it is connected to tube 102 to receive pressure from tube 102. Pneumatic pressure switch 106 is electrically connected by wires 108 and 110 to fan motor 50 and pump motor 62 respectively.

The method of operation will now be described. If the temperature and humidity in the enclosure are below the settings of the thermostat 66 and humidistat 68, the pressure in tubes 72, 76, and 78 are insufiicient to actuate pressure switch 86, and therefore the solenoid valve 32 is closed and motor starter 90 is open so that the refrigeration system is not energized. Since the refrigeration system is not energized, the pressure in pipe 34 is insufl'iclent to close pressure switch 106, and therefore fan motor 50 and pump motor 62 are not energized.

As the temperature or the humidity in the enclosure 10 approaches the control point, the thermostat 66 and the humidistat 68 transmit to tubes 76 and 72 respectively, a pressure proportional to the deviation from the control point. When the pressure in line 78 increases to a predetermined point, as for instance 10 pounds, the pressure switch 86 closes to open the solenoid liquid valve 32 and to start the compressor 22 through starter 90. The dampers 82 are partly open, because they start to open at 8 pounds and are fully open at 12 pounds. If the temperature of the enclosure is above the control point the thermostat 66 will transmit a pressure in excess of 6 pounds and dampers 94 will be closed so that condenser 20 does not heat the air. If after a period of operation the temperature drops below the control point, the pressure in line 76 will drop below 6 pounds and the dampers 94 will open to provide the necessary reheat from condenser 20. If the humidity also drops below the control point the pressure in tube 78 will drop below 6 pounds at which pressure the pressure switch 86 will operztzto close'solenoid valve 32 and to stop the compressor Presser controller 98 has an output air pressure proportional to the refrigerant condensing pressure and does not put the fan motor 52 and the pump motor 62 into operation until the pressure in line 34 exceeds a predetermined limit. A substantially constant pressure and temperature in pipes 34 and 26 is thus maintained. With the pressure and temperature of the supply to condenser 20 maintained substantially constant, the dampers 94 and 96 can control the temperature of the air entering enclosure 10 through opening 15.

When the pressure in pipe 34 exceeds a predetermined limit, indicating the need for additional condensing ca pacity, pressure controller 98 transmits pressure proportional to the refrigerant condensing pressure from the source to the pressure switch 106 sufi'icient to actuate pressure switch 106, thus starting fan motor 50 and pump motor 62 through wiring 108 and 110 respectively. When evaporative condenser 38 is in operation, a substantially constant pressure and temperature is maintained in pipe 34 by dampers 54 and 56, and 58 which control the amounts of outside air and recirculated air flowing through the evaporative condenser in proportion to small changes in the refrigerant condensing pressure. When the pressure in pipe 34 is just sufiicient to actuate pressure switch 106, dampers 54 and 58 are closed and dampers 56 are open. If the pressure in pipe 34 continues to increase, the pressure controller 98 increases the pressure transmitted to tube 102, and damper motor 104 moves the dampers 54 and 58 toward open position and the dampers 56 toward closed position.

It should be understood that a temperature controller can be used in place of the pressure controller 98 because the condensers 20 and 36 maintain a saturation condition in which for each temperature there is a corresponding pressure.

Although the preferred embodiments of the invention have been specifically described, it is contemplated that many changes may be made without departing from the scope or spirit of the invention, and I desire to be limited only by the claims.

'I claim:

'1. Apparatus for conditioning air for an enclosure comprising an evaporator, a condenser, a compressor for moving refrigerant from the evaporator to the condenser, said condenser having primary and secondary elements connected in parallel relation, means for circulating a fluid in heat exchange relation with said secondary element of said condenser, means for moving air for the enclosure, first over said evaporater, then over the primary element of the condenser and then into the enclosure, means for by-passing part of the air around said evaporator, and means responsive to the temperature of the air of the enclosure for controlling the damper means.

2. Apparatus for conditioning air for an enclosure comprising an evaporator, a condenser, a compressor for moving refrigerant from the evaporator to the condenser, said condenser having primary and secondary elements connected in parallel relation, means for circulating a fluid in heat exchange relation with said secondary element of said condenser, means for moving air for the enclosure, first over said evaporator, then over the primary element of the condenser and then into the en closure, means for by-passing part of the air around said evaporator, damper means for varying the amount of air by-passing said evaporator, and means responsive to the temperature and humidity of the air of the enclosure for controlling the damper means.

3. Apparatus for conditioning air for an enclosure comprising an evaporator, a condenser, a compressor for moving refrigerant from the evaporator to the condenser, said condenser having primary and secondary elements connected in parallel relation, means for circulating a fluid in heat exchange relation with said secondary element of said condenser, means for moving air for the enclosure, first over the evaporator, then over the primary element of the condenser, and then into the enclosure, means for by-passing part of the air around said evaporator, first damper means for varying the amount of air by-passing said evaporator, means responsive to the temperature and humidity in the enclosure for controlling said =first damper means, means for by-passing part of the air around said primary element of said condenser, second damper means for varying the amount of air by-passing said primary element of said condenser, and means responsive to the temperature of air in the enclosure for controlling said second damper means.

4. Apparatus for conditioning air for an enclosure, comprising an evaporator, a condenser, a compressor for moving refrigerant from the evaporator to the condenser, said condenser having first and second portions connected in parallel relation, means for conveying air for the enclosure in heat exchange relation with the evaporator to remove heat therefrom, means for conveying the air thus treated in heat exchange relation with the first portion of the condenser for increasing its dry bulb temperature, means for conveying the air which has been in heat exchange relation with the first portion of the condenser to the enclosure, means for moving a fluid in heat exchange relation with the second portion of the condenser, means responsive to a condition of insuflicient condensing capacity in the first portion of the condenser for rendering said fluid moving means operative and means for conveying a portion of said fluid leaving said second portion of the condenser again into heat exchange relation with said second portion of the condenser.

References Cited in the file of this patent UNITED STATES PATENTS 1,837,798 Shipley Dec. 22, 1931 1,986,863 Terry Ian. 8, 1935 2,154,136 Parcaro Apr. 11, 1939 2,619,802 Kline Dec. 2, 1952 

